Research Summary

Professor Nag's lab develops unique peptide or peptidomimetic macrocycles using robust chemical reactions and Solid Phase Peptide Synthesis. Macrocycles, with molecular weights of approximately 1000, bridge the gap between small molecules and proteins, in terms of size and composition. Chemical synthesis of macrocycles allows one to incorporate unique properties such as thermal and protease stability and inclusion of small molecules. Harnessing the power of molecular recognition in macrocycles, we currently are working on different aspects of biological chemistry and catalysis.

Currently her group is focused on the following themes:

1. Macrocyclic peptides as potential Cancer Therapeutics Intracellular regulatory proteins involved in cell signaling frequently interact with each other through large surface areas, a phenomenon termed as Protein Protein Interactions (PPi), and aberrant PPI can lead to diseases like cancer. Peptide macrocycles, with their extended structures, can occupy efficiently the large protein surfaces involved in PPI, and therefore can inhibit prevent aberrant intracellular PPI. The Nag lab is developing a technology to synthesize and screen novel peptide macrocycles which can penetrate the cell membranes and selective target the protein interaction surfaces.

2. Designing biomimetic catalytic centers

Complexes of transition metals like copper and nickel with peptide and peptidomimetic macrocycles can be visualized as miniature versions of photosynthetic proteins such as Photosystem I and Photosystem II. While the proteins are excellent catalysts, they degrade rapidly outside the cellular environment. The Nag Lab is trying to optimize the motifs of known linear peptides, as complexes with metals, for efficiency as water oxidation catalysts. Future work will involve development of unique macrocycle –metal or organic ligand - metal catalytic centers as catalysts for homogeneous and heterogeneous water oxidation and carbon dioxide reactions.

3. Developing biological small molecule sensors

Building on our previous research on selective recognition of phospho-serine and phosphorylated proteins, we plan to develop macrocyclic reagents for recognition of phosphate containing biological small molecules. Selective recognition will involve not only the phosphate moiety sensing but also unique sensing of other parts of the small molecule. Unique elements in the macrocycles will enable phosphate recognition while amino acid components of the macrocycle will allow selective recognition of the small molecule.